Bush chisel



Jan. 3, 1933.

P. P. BICKNELL 1,893,355

BUSH CHISEL Filed Feb. 24, 1931 Inventor j I 4 Palnauaffliz'hmll Patented Jan. 3, 1933 v I PUTNAM r. IBICKNELL, on nooxmiun, MAINE BUSH cnlsnr;

Application area February 24,.1931. Serial a... 517,733. i

This invention relates to bush chisels and particularly to an improved or novel type of these tools which are generally old and standard in the stone working industry. These tools have for many-years been fitted with detachable cuts removably held in a head by which they could be directed against the sur-. face to be worked. V

Various efiorts were made to improve the manner of holding the cuts so that they would be readily removable but firmly held and not subject to being loosened by the shocks and strains of the chisel when in use.

It was conceived that a system of wedging was desirable and for a long time bush chisels had their cuts wedged in place,.such wedging showing in many respects an improvement over earlier types of fastening. The dif ficulty was that under the constant shock of the tool in use there was a continuous loosening tendency and in attempting to keep the cuts tight in the head, the thin flat wedges were over-driven expanding the jaws of the head and eventually rendering it useless. The wedging of the cuts also involved a necessity of holding the cuts against displacement by the wedge and while holding means were devisedQthese also produced elements of dimculty sides of the head they were eventually a victim of an accidental stroke of the hammer in tightening the wedge. All these and various other difliculties are well known to the trade and have been the subject of various eflorts to overcome them.

My present invention involves certain principles of construction which without detracting from the original utility of the bush chisel as such makes it a highly eflicient tool and one capable of long and constant service.

As illustrative of my invention I have shown in the accompanying drawing a characteristic tool illustrative of the principles 5 involved and in itself one of great efliciency in use and economy in manufacture. v In the drawing: 7

Fig. 1 is a side elevation of such a bush chisel.

Fig. 2 an enlarged side view of the head.

because if theyprotruded beyond the .7 prevents the dislodgement of the cuts 4:

- a fragmentary sctioh f the needle right angles to Fig. 2. Fig. 4 anendview of the head. r Fig. 5 a side-view of my tapered wedge of cylindric section. v v

Fig. 6 an enlarged view of the same, and

j Fig. 7 is afragmentary view of a out showingits notched or channeled end.

My tool comprises a head l having a pole 2.

The head 1 is recessed as at 3 for receiving cuts as 4. The head 1 is divided by the recess 2 into externally rounded lateral jaws 1 into the sides of which are fitted the ends of the bail orhandle 5. At the bottom por- .tion of the recess 3 is located a gib '6 adapted to receive the end thrust of thecuts 4:. This gib, has a rib 7 transversely-of the cuts and interengaging the corresponding recess or groove transversely of the set of cuts. The gib 6 is-flushed with the side face of the head am land held in place by studs 8. One wall of therecess 8 iscut with agroove Q of slightly conic taper,.that is, it is of conic section cut parallelto the cone axis. ".With this I provide av wedge 10 having a conic face 10 corre- I spond to that of the groove 9 and a fiatface l0 'adaptedto bear; against the end cut of a set.'

Owing to the conic relation between the wedge and the groove the expansion resultants instead of being directly transversely of the jaws is radially distributed. This relieves the head in a remarkable degree from the old spreading tendency of the flat wedge. It enables thewedge to be tightly driven without springing the jaws and necessitating a further and more damaging driving of the wedge.

The gib 6 being flush with the face of the head 1 is in no danger of damage from a mistaken blow intended for the end of the wedge. It is amp-lysustained by the pins 8 against any dislodgement and in turn through its rib whilethe wedge '10 is being driven. The rib' Q7 and groove in thecuts may be of any shape or of reversed relation or otherwise formed toprovide an interengagement between the gib 6 and the end of the set of cuts- 4. The gib 6 also may be held in any convenient Way but preferably by means which Will permit it to have its ends flush with the face of the head. 7 r

Bush chisels in accordance with my invention may be of any design or size and adapted to take any number of cuts. I The bail 5 pivoted to the sides of'the jaws makes an extremely convenient Way of steadying thm 10 chisel and various other features and improvements may be designed, modified or combined, all Without departing from the spirit of my invention. l/Vhat I therefore claimand desire to secure by Letters Patent is 1. In a bush chisel or like tool,'a head having a two jaw recess for the cuts, the side Walls of the recess being vert1cal,"one Wall of said recess 'h'aving a horizontal transverse groove of rounded cross section, a set of cuts disposable therein and having recessed ends,

a wedge of conic sectional form for: said groove having aflat face adapted to bear on one side of the cuts to Wedge them in the head,

2 a'gib in the bottom of the recess and'disposed for hearing on the cut ends, said gib having arib disposed transversely of the cuts to engage the recessed ends thereof. 2. In a bush chisel or like vertical impact tool, a head having a cut receiving open sided recess defined by opposite jaws having flat parallel inner faces forming the side Walls of the recess, one of said Walls'having a horizontal transverse open groove of rounded 3 and tapered cross section extendingacross the wall face to the open sides thereof, a set of flat face cuts disposed with their ends insaid recess between said'jaw faces, and a Wedge-of half conic section fitting said tapered groove 4 and havinga flat cut contacting face maintained-parallel with the planes of the cut faces and cut ends and-at right angles to the vertical axis of impact of said tool.

'In testimony whereof I aflix m signature.

PUTN AM P. BI KNELL. 

